Gaps form when conventional flaps/control surfaces are in the extended state. These permit the air to flow through, which reduces the efficiency of the flap and generates noise. The radar signature is a further issue, particularly in the military. Surface waves are emitted at gaps of this type. A conventional method for reducing this is clipping, i.e. rounding off sharp edges on the control surface.
A transition portion is known from US 2011/0303796 and forms a continuous contour across a gap. For this purpose, the transition portion comprises a plurality of ribs which can be pivotally fastened to a base part, wherein the transition is achieved by each of the adjacent ribs being substantially pivoted in a stepped manner until overall deflection is reached.
DE 91 13 090 U1 describes an option of closing a gap between a flap and a laterally adjacent fixed edge of a wing by means of a plate. In this regard, a triangular plate part can be provided, one side of which is articulated to the lateral edge of the flap, and the other side of which is held in a gap in the edge of the wing edge so as to be insertable and retractable and pivotable. In this case, at least one side has to allow for a change in length by displacement, which change is caused by a change in the angle between the flap and the wing edge.